Laurentia, Blue Stars

Lovely  Laurentia or Blue Stars

Laurentia with geranium and calibrachoa
It’s not as common as some other annuals but every year I search out some laurentia (Isotoma axillaris) for my porch.  I have been growing it for years and I really enjoy the light sweet scent it emits in the evening.  If you have never tried this plant you are missing a summer treat.  This plant is sometimes called blue star or blue star creeper but those common names are also used for a cousin of the plant that’s sometimes used as a groundcover but has a much shorter bloom period.  Laurentia comes from a former classification of the plant, it should probably be called Isotoma but I am used to the name Laurentia as are many gardeners.

Laurentia/Isotoma is native to Australia.  It’s really a perennial that’s very frost tender, so it’s treated as an annual here.   It’s a low growing, mounded plant about 12 inches high with dainty, fine foliage that would be good for front of the border or what I love it for, containers.  It’s relatively new to the bedding plant scene, at least in the US.  ‘Beth’s Blue’ a Proven Winners selection is the cultivar I normally end up with but there are a few other selections out there including ‘Indigo Stars’, ‘Avant- Garde blue’, and ‘Avant-Garde pink’ that you may find.  Generally gardeners will want to start with plants, but seeds are available in some catalogs.

The 1 inch lavender blue flowers of Laurentia are star shaped and the plants are generally covered in bloom through the summer, although in really hot weather I notice that blooming slows sown.  The plant doesn’t need dead heading to keep blooming.  I have seen butterflies check out the flowers although bees don’t seem particularly interested in them.  The sweet scent of the flowers is stronger in the evening but it’s never over powering. Nurseries have produced deeper blue, pink and even white flowered selections but it’s still hard to find those.

The leaves of Laurentia are long and narrow, with odd shaped projections or teeth scattered irregularly along the edges. Laurentia is considered to be drought and heat tolerant.  It is not tolerant of cold and should be put outside after all danger of frost has passed.  I have tried over wintering the plant inside a few times but with no success.

Laurentia prefers full sun but mine blooms nicely on the deck where it gets full sun for some morning and late day hours but is shaded in the middle of the day. It likes a rich but well drained soil and prefers to dry out slightly between watering.  Container plants that get too dry however, will quit blooming.

Laurentia does need some fertilization for best bloom, like most container plants.  Mix slow release fertilizer for blooming plants in the potting soil or use a liquid fertilizer once a week.   I use the slow release fertilizer when planting and then start liquid fertilizer in late July, as I do with most of my containers.

The foliage of Laurentia has a milky sap that can cause skin irritation if broken stems are handled.  You probably won’t want to use it as a cut flower but this rarely poses a problem in containers or the garden.  That sap does make the plant off limits to most animals like deer and even insects don’t munch it.

Laurentia is pretty, fragrant, easy to grow and deserves a place in your garden.


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